Electroplating



a bath.

Patented Aug. 11, 1931 UNITED STATES PATENT OFFICE LEON It. WESTBROOK,0F CLEVELAND HEIGHTS, OHIO, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO THEGRASSELLI CHEMICAL COMPANY, OF CLEVELAND, OHIO, A COR- POBATION orDELAWARE ELECTROPLATING No Drawing.

baths, of a brightening agent and an organic addition agent.

Practically all addition agents which so far have been found to bebeneficial in their action are of a more or less colloidal organicnature and of ill defined and possible varying composition so that it issometimes difficult to determine from a chemical analysis if a givenmaterial will produce constant and reproducible results in anelectroplating I have now found that certain so-called dyestuffintermediates which are commercially available in constant andanalytically determinable purity are particularly suited as additionagents to electroplating baths.

They are naphthalene compounds which couple with dia-zo compounds andare of an acidic nature, and my preferred addition agents are chemicallydistinguished by being compounds in which the naphthalene nucleus issubstituted by an acidic radical such as the sulfo or carboxylic groupand by an amino or hydroxy group or both the latter. It is, of course,necessary that such compounds be water soluble, or soluble in thecadmium-cyanide bath.

My novel cadmium plating baths are produced by dissolving in water acadmium compound, a cyanide, other electrolytes required to promote theelectrodeposition of cadmium, and a small amount of a naphthalenecompound containing an acidic group and being capable of coupling withadiazocom- 4 pound. Amongst the other electrolytes re- Application filedFebruary 23, 1928. I Serial No. 256,493.

quired to promote the deposition of. commercially valuable chromiumplates, I refer particularly to the so-called brightening agents bywhich I mean the nickel or copper salts as disclosed in my Patent No.1,681,509, granted August 21, 1928.

Such a plating bath 'is then used in the conventional manner at theusual temperatures and current densities. The plates obtained are,however, superior in brightness and adhesiveness to those obtained froma similar bath in which theaddition agent has been omitted.

A typical representative of such a novel bath is obtained by dissolvingin water, to 1 liter, the following:

-Grams NaCN 120 0& 011), 4s Na SO n soim o 1 10 to 15 grams of one of mynovel addition agents or a mixture of such agents is then. dissolved inthis bath and, using a cadmium anode and the article to be plated as thecathode, the current is passed through the bath at the usualtemperatures and current densities.

. Typical representatives of the class of naphthalene compounds which Ifound to ,be most useful as addition agents are reprefonic acid).

Naphthionic acid (l--naphthylaminesulfonic acid).

G salt (sodium-beta-naphthol-G-8-disulfonate). It is well known thatthese compounds will easily couple in aqueous solution with aromaticdiazo compounds.

Amon st these I found the naphthylamine monosul onic acids, such as theF, Cleves,

and Laurents acids, to have the most bene- 'ficial efi'ect. I

It is immaterial whether the free acids or their water soluble salts aredissolved in the cadmium cyanide bath, and both can, for purposes ofthis invention, be considered entirely equivalent.

I claim:

1. An electroplating bath comprising an aqueous solution containing acadmium comu" pound, a cyanide, a brightening agent, and

an acidic naphthalene compound capable of coupling with a diazocompound.

2. An electroplating bath comprising an aqueous solution containing acadmium com- ;5 pound, a cyanide, a brightening agent, and

a naphthalene sulfonic acid compound capable of coupling with a diazocompound.

3. An electroplating bath comprising an aqueous solution containing acadmium compound, sodium cyanide, a brightening agent,

and anaphthylamine monosulfonic acid compound.

4. An addition agent for cadmium cyanide electroplating baths comprisingan acidic '85 naphthalene compound capable of coupling with a diazocompound.

5. An addition agent for cadmium cyanide electroplating baths comprisinga naphthalene sulfonic acid compound capable of coupling with a diazocompound.

6. An addition agent for cadmium cyanide electroplating baths comprisinga na hthylamine sulfonic acid compound.

An electroplating bath comprising an aqueous solution containing acadmium 'compound, a cyanide, and an acidic naphthalene compound capableof coupling with a diazo compound.

8. The process of producing bright adherent cadmium plates whichcomprises electrodepositing cadmium from an aqueous solution containinga cadmium compound, a

cyanide, and an acidic naphthalene compound capable of coupling with adiazo compound.

9. The process of producing bright adherent'cadmium plates whichcomprises electrodepositing cadmium from an aqueous solution containinga cadmium compound, a cyanide, a brightening agent, and an acidicnaphthalene compound capable of coupling with a diazo compound.

.10. The process of producing'bright ads herent cadmium plates whichcomprises electrodepositing cadmium from an aqueous ture.

LEON R. WESTBROOK.

